A Soft Start Method for Doubly Fed Induction Machines Based on Synchronization with the Power System at Standstill Conditions
José M. Guerrero,
Kumar Mahtani,
Itxaso Aranzabal,
Julen Gómez-Cornejo,
José A. Sánchez,
Carlos A. Platero
Affiliations
José M. Guerrero
Department of Electrical Engineering, Escuela de Ingeniería de Bilbao, Universidad del País Vasco—Euskal Herriko Unibersitatea, 48013 Bilbao, Spain
Kumar Mahtani
Department of Electrical Engineering, Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain
Itxaso Aranzabal
Department of Electrical Engineering, Escuela de Ingeniería de Bilbao, Universidad del País Vasco—Euskal Herriko Unibersitatea, 48013 Bilbao, Spain
Julen Gómez-Cornejo
Department of Electrical Engineering, Escuela de Ingeniería de Bilbao, Universidad del País Vasco—Euskal Herriko Unibersitatea, 48013 Bilbao, Spain
José A. Sánchez
Department of Hydraulics, Energy and Environmental Engineering, Escuela Técnica Superior de Ingenieros de Caminos, Canales y Puertos, Universidad Politécnica de Madrid, 28040 Madrid, Spain
Carlos A. Platero
Department of Electrical Engineering, Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain
Due to their exceptional operational versatility, doubly fed induction machines (DFIM) are widely employed in power systems comprising variable renewable energy-based electrical generation sources, such as wind farms and pumped-storage hydropower plants. However, their starting and grid synchronization methods require numerous maneuvers or additional components, making the process challenging. In this paper, a soft start method for DFIM, inspired by the traditional synchronization method of synchronous machines, is proposed. This method involves matching the frequencies, voltages, and phase angles on both sides of the main circuit breaker, by adjusting the excitation through the controlled power converter at standstill conditions. Once synchronization is achieved, the frequency is gradually reduced to the rated operational levels. This straightforward starting method effectively suppresses large inrush currents and voltage sags. The proposed method has been validated through computer simulations and experimental tests, yielding satisfactory results.
